Tobacco is used more frequently during pregnancy than any other substance, including alcohol, marijuana, and cocaine. In addition, unlike other drugs of abuse, women who use tobacco prenatally rarely decrease or abstain from use upon learning of their pregnancy. Thus, prenatal tobacco exposure is of major public health concern due to the potential negative health outcomes for both mothers and their offspring. Furthermore, animal studies have demonstrated a direct link between prenatal tobacco exposure (PTE) and deficits in central nervous system development. More specifically, studies in humans have established that PTE leads to attention deficits such as inattention, increased impulsivity, and an increased risk for Attention Deficit Hyperactivity Disorder (ADHD). The underlying behavioral and brain mechanisms of the specific attention deficits that result from PTE have not been characterized. The purpose of the proposed study is to characterize the effects of tobacco on behavioral and brain function measures of attention. We will examine how prenatal exposure to tobacco affects different aspects of attention, including alerting, orienting, and executive control of attention, both behaviorally and by probing the integrity of the neuronal circuitry that supports these functions. To do this, we will use state-of-the art behavioral measures of cognitive function and fMRI neuroimaging techniques. Subjects for the proposed study will be young adults selected from the Maternal Health Practices and Child Development Project (MHPCD) cohort, a longitudinal study of the effects of prenatal substance exposure on growth, behavior, and cognitive function. Two exposure groups are defined: tobacco only (TOB), and no exposure to tobacco (Controls). To the extent that the proposed research program can identify deficits in cognitive and brain function, the proposed line of work can potentially provide crucial information for the identification, intervention, and rehabilitation of individuals exposed to tobacco during pregnancy.